Gravity liquid separator



K. F. TROMP GRAVITY LIQUID SEPAHATOR Filed Sept. 18, 1945 FlGllb INVENTOR KLASS F'. T N Br Fla? AGENTS Patented Jan. 4, 1949 UNITED ST y Q'FFICE; GRAVITY in -Mme. I 1

of three-fourths to Domanialer Mijn-Maatschappij. N. V., Kerkrade, N etherlands" In Germany September 5', 1941 Section 1, Public Law 690;. August 8;. 1946 Patent expires September 5,1961.

This invention relates to apparatus for separating, by means of a suspension of sand in water/7 solid materials having diiierent specific gravities.

Hereinafter the word watef will be used to mean any liquid suitable for the purpose, and the word sand will be used to mean any comminuted insoluble material, for instance magnetite, heavier than the liquid and adapted as the solid constituent of the suspension.

More especially the invention relates to an improvement in apparatus as disclosed by my copending United States patent application Ser. No. 335,078, filed. May 14, 1940, now Patent No. 2,365,734, December 26, 1944. Said apparatus comprises a tank for holding a body of suspension of sand in water and provided with means for removing material from the bottom thereof, means for removing material from the surface of said body, means for feeding the materials to be separated into said tank at one side thereof to permit them to respectively seek zone levels corresponding to varying specific gravities of the materials, independent means for introducing suspension at the feed side of the tank and for withdrawing suspension therefrom at the opposite side thereof, said suspension introducing and withdrawing means serving to create a slow moving substantially horizontal current in said tank for conveying materials to be separated thereacross, and means at the said opposite side of the tank for removing material from a level intermediate the bottom of the tank and the surface of the body of suspension.

In accordance with my aforesaid copending specification, the material held in suspension between the top and the bottom level of the bath is removed from the tank by a hydraulic or fluid discharge, i. e. by an upwardly directed How of liquid.

In practice it has been found that under certain circumstances said fluid discharge is not a1-' together satisfactory, and the object of my present invention is to substitute it by mechanical means more capable of dealing with relatively large quantities of middlings and less liable to disturb the uniformity of the substantially horizontal flow of the suspension in the-tank than the drag conveyor disclosed, for said purpose, in my prior United States specification No. 2,139,047. With this object in view, my invention consists in that the discharge end of the tank is constituted as an upwardly inclined chute, whose upper end is located some distance below the surface of the bath and communicates with a discharge trough,

3- Claims. (01. 209-173) said chute. cooperating with an. impeller driven: in such. manner as, to. be: adapted to puslr middlings through the. chute towards; the disecharge trough, thereupon to be lifted. from the; bath and to againbe dipped thereinto near the inner end. of the chute; to force; another amount, of. middlings towards said trough, in cyclic suecession. l

Inorder that my inventionmay be fully. understood. by those skilled in the art, Ishallnow proceed to describe it, with referencelto the-annexed, more or less diagrammatic drawing, wherein:

Figs. la. and 1b are longitudinal. vertical sectional. views of the feed. end. andof thedischarge end, respectively, of, apreferred embodiment of my invention,

Fig. 2 isa fragmentary plan view of said. embodiment, and.

Fig. .3 is a.diagramoitheimpeller movement.

In Figs. 1a and 1b,. the. numeral 4 designates the; tank. holding a body 5 of. unstable suspension. of sand. in water. As shown, the tank is of elongatedform and comparatively shallow, its side. walls. 6. and I being substantially paralleland vertical-L; A drag. conveyor 8. driven in clockwise; direction and extending through. the: iull. length. of the tank ismountedinthelower portion. thereof, so that. its lower part is. adapted to sweep the. tank bottom. andito dragany material lying there; ontowards asloping, discharge chute 9. A second drag conveyor l0, driven. in anticlockwise. direc tion, is. mounted with a portionof. itsloawer. part.v

parallel and a certain distance below thelevel H- of the body. of suspension. within, the; tank,,.a. further portion of said part being parallel. and flush with. an upwardly inclined/chutell. The; lower end ofsaid chute extends downwardly to a. smalldistance below. the. level I. I itsupper end merging, above said level, into a transverse. and sloping trough l3.

The left hand or feed-side. of the tank. isprovided with three vertically spacedinlet. openings. l4, 5,. I6 for suspension of sand in water. fed thereto bycond'uits I1; l'flandllll, respectivelythe materials to be. separatedfbeing, charged'into/ the.

tank by a chute 20 openingvertically above said? inlet openings substantiallyat the surface of the. bath.

The arrowsp designate the direction in which thesuspension fed to the bath flows from the feed" side towards the opposite or discharge side. ofthe.

tank.

Located beyond'thei chute P2,. as seen inthe" direction of flow ofthesuspension, at a. leveli just;

above that-oftheupperpartofjconveyorcj e1 front edge of the aforesaid inclined chute 24, which forms part of the right hand end wall 24a of the tank and extends upwardly to a level some distancebelow the surface ll of the bath, its upper end 24b merging into a sloping discharge trough 25 and forming a weir or overflow edge.

The impeller, which cooperates with chute 24 to remove middlings from the bath, is designated by 26. In the position shown in Fig. 117, it is situated with its lower edge vertically above the front end of chute 24 and at a very smalldistance above the bottom of the chute. formed by a board extending across and through the full width of the chute, and is secured to the Intermediate pivot 29 and shaft 3|, the lever 30 carries the pivot 36 of a bell-crank 31, one arm of which is secured by a strap 38, to a short arm 39 of rod 21, the other being provided with an antifriction roller 31a held in engagement, by the gravity of the impeller 26 and of the rods 21, 28,with the circumference of a second cam keyed to shaft 3|.

From the drawing itwill be understood that, if shaft 31' is rotated in counterclockwise direction at a speed of say 2-3 revolutions per minute,

starting from the positions of the various parts as shown, lever 30 will during the greater part of the cycle remain stationary, since roller 33a travels on a concentric portion of its track on cam 35. During said period, roller 31a is slowly pushed away from shaft 3|, owing to the radius of cam 40 slightly but progressively increasing. Consequently, the impeller 26 will move towards the right, over chute 24, at a low, progressively increasing speed, until it has reached the discharge end thereof.

At this moment, roller 33a rides up an enlarged portion of restricted angular extent of cam 35, whereby the lever 30 is swung upward and the impeller is rapidly raised from the bath. About simultaneously therewith, roller 31a rides down a first steep slope of cam 40, so that the impeller 21 resumes its substantially vertically depending position, and immediately thereafter roller 33a rides down the aforesaid enlarged portion of cam 35, while roller 31a rides down a second steep slope of cam'40, owing whereto the impeller, notwithstanding the downwardly swinging movement of lever 30, remains substantially vertical while again being dipped into the bath and returning into its initial position. Thereupon the described cycle is repeated. 7

The apparatus described operates as follows. Assuming run of-mine coal and suspensions of the required densities to be fed at suitable rates into the. bath by chute 20 and by the inlets l4-l6, respectively, drag conveyors 8 and ID to be driven and shaft 3i to rotate at suitable low speeds, it will be understood that the gravimetric separation of the material treated in the tank will take place in substantially the same manner as disclosed by my prior. U. S. Patent 2,139,047 and my copending U. S. patent application Serial No.

335,078. That istosay, the pure coal will float,

Itis' .a,b,c,..

4 chute l2 and dragged thereby into the discharge trough [3. The discharge of the coal from said trough may be promoted by a jet of suspension from pipe 4! shown in Fig. 2.

The middlings, which pass below the front edge of chute l2, enter into the chute 24 and are driven towards the overflow 24b.

.As to the slate, this sinks to the bottom, from which it is removed by the conveyor 8.

Fig. 3 diagrammatically illustrates the movement of the impeller 26, successive positions of which during a complete cycle are designated by n, it being understood that all distances from a to b, from b to c, and from nto a are covered in say one second. In view of the explanation given hereinbefore, it is not necessary to go into a detailed description as far as the operation of the impeller is concerned. I only wish to point out that the speed of the impeller, through the first part of its outward excursion, should be approximately equal to that of the suspension when entering the chute, so that the impeller, while still assuming a substantially vertical position, simply follows-the movement of the liquid. That is to say, it allows the liquid on its rear face to continue to fiow along substantially horizontal paths, and simultaneously prevents the middlings in front of it from following their tendency to lag behind under the influence, inter alia, of frictional resistance offered by chute 24. As to the liquid between the level of the top edge of the impeller and the surface of the bath, this will practically not at all be interfered with by the impeller, but continue its slow horizontal movement towards the weir 24b, thereby preventing the middlings, which are pushed towards the weir by the impeller, from returning over the top edge of the impeller. Thus, no disturbances are set up in the uniform, horizontal flow of the suspension in the bath on the left hand side of chute 24, and the accuracy of the separation therein is not impaired.

During the last part of its outward stroke, the deviation of the impeller from its vertical position is more appreciable so that the speed of the suspension in the lower portion of the chute will acquire a slight upward inclination. This, however, does not appreciably affect the uniformity of flow in the main portion of the separation tank, especially not as during said part of the outward stroke the impeller is accelerated to keep pace with the flow of the suspension towards the weir 24b, so that said deviation is only of short duration.

The arrows p in Fig. 3 denote that the velocity of ilow of the liquid in the tank gradually decreases from top to bottom, 1. e. from the speed of the conveyor ill to that of the conveyor 8. This, however, it not always necessary.

As a matter of course, the suspensions discharged from the tank, after separation from the materials, will be regenerated and recycled. The means therefore, however, have not been illustrated, since they do not form part of my present invention.

What I claim is:

1. Apparatus for separating, by means of a suspension of sand in water, solid materials having different specific gravities, comprising a tank for holding a body of suspension and provided with means for removing material from the bottom thereof, means for removing material from the surface of said body, means for feeding materials to be separated into said tank at one side thereof to permit them to respectively seek zone levels corresponding to their specific gravities, independent means for introducing suspension at the feed side of the tank and for withdrawing suspension therefrom at the opposite side thereof, said suspension introducing and withdrawing means serving to create a slow moving substantially horizontal current in said tank for conveying materials to be separated thereacross, and means at the said opposite side of the tank for removing material from a level intermediate the bottom of the tank and the surface of the body of suspension, wherein the latter means comprise, in addition to an upwardly inclined shoot provided at the discharge end of the tank with its upper end somewhat below the surface of the bath, an impeller element and driving means therefor, said driving means being arranged for imparting cyclic movement to the impeller element in such a manner that said 618- ment is first swept in an accelerated movement over said upwardly inclined shoot, thereupon lifted from the body of suspension, and thereupon returned to again be dipped into said body near the lower end of the shoot.

2. Apparatus as claimed in claim 1 and comprising a first lever from which the impeller is flexibly suspended and which is adapted for swinging movement about a fixed axis, a second lever operatively coupled with the first lever and also adapted for swinging movement about a fixed axis, a drive shaft, a cam operatively associated with said shaft and adapted to impart swinging movement to said second lever, a third lever hinged to said first lever and operatively coupled with the impeller, and a second cam operatively associated with said shaft and adapted to impart swinging movement to said third lever.

3. Apparatus as claimed in claim 1, wherein the impeller element has a width substantially equal to that of the shoot and is arranged to sweep without appreciable clearance over the bottom of the shoot.

KLAAS F. TROMP.

REFERENCES CITED The following references are of record in the file 'of this patent:

UNITED STATES PATENTS Number Name Date 1,215.345 Clark Feb. 13, 191 2,139,047 Tromp Dec. 6, 1938 

